The present invention relates to sheet feeding and registration apparatus and in particular to a stalled roll registration apparatus.
The automatic reproducing machines using electrostatographic reproduction methods available on the market place today have a wide variety of capabilities and utilities. They extend all the way from the high speed multi-functioned 9000 family of products available from Xerox Corporation to the smaller more compact machines which rely on the manual feeding of documents and copy paper. In all these devices, it is desirable to have reliably consistent feeding of copy sheets. It is desirable for example in any paper feeder to know and control with some degree of reliability where the paper is at all times. This is to ensure accurate registration and a minimum amount of skew of the lead edge of the paper, in relationship to the lead edge of the image on the photoconductor imaging layer. One of the many type of paper feeders that has been used, particularly in the smaller more compact copiers is that which is referred to as the stalled roll paper feeding and registration system. In such a system the lead edge of a copy sheet is separated from the input paper stack and fed by a feed roll or other feed means to a stalled registration roll, typically to the nip formed between such a roll and an idler roll in contact with it where the lead edge is deskewed and the paper is registered in the shortest distance from the feed supply, thereby ensuring accuracy of registration and deskewing. In the Xerox 1020 machine, for example, the paper feeder and registration functions are accomplished via a sheet separator feed roll module apart from a stalled roll registration module. Each of the driven shafts with the feed roll and the registration roll have a clutching mechanism with a pivoted arm between the two shafts controlling the two shafts. Each shaft has a control collar with multiple teeth and there is a switch in the paper path to identify paper location in response thereto to activate a solenoid which in turn activates the control arm and thereby the individual control collars. This device requires a complex, costly electronic controller device to look at and sense what is going on with regard to the sheet being fed and to switch the feed roll and registration roll on and off. In addition, the retraction of the control arm from the control collar is inconsistent with respect to time on the registration roll clutch thereby leading to the propensity for increased mis-registration with the image on the imaging layer. Furthermore with the feed system used in the Xerox 1020, for example, a separate means to retract the feed roll from the sheet supply must be provided, otherwise the top sheet being fed from the supply of sheets will be under the influence of both the feed roll and the registration roll, again giving rise to the possibility of poor registration and accuracy with regard to the lead edge of the image on the imaging surface.